CN112557130B - A method of filling gas detector with gas - Google Patents

Abstract

The invention discloses a method for filling a gas detector with gas. The gas filling method includes step S: first, cleaning the gas detector repeatedly for many times to eliminate the influence of memory effect on measurement accuracy; step T: then filling the gas The detector is charged with a sample of radioactive xenon gas required to calibrate the relative detection efficiency. As an auxiliary technology specially used for the determination of some basic performance parameters of the gas detector, the invention adopts the pipeline vacuum buffer technology, which can effectively clean the gas detector and charge the radioactive xenon gas sample required for calibrating the relative detection efficiency; It meets the requirements of narrow pressure range, high pressure precision control and many repeated operations for gas detectors, and provides solid technical support for the development of gas detectors.

Description

A method of filling gas detector with gas

technical field

The invention belongs to the technical field of measurement, and in particular relates to a method for filling gas into a gas detector.

Background technique

Xenon in the atmosphere is enriched by adsorption, separated and purified, and then measured for radioactivity. The gas detector is the core component of a high-sensitivity radioactive xenon measurement system. Its performance is mainly based on standard sources and irradiated gas samples for testing and investigation. Obtain basic performance parameters such as leak rate, energy resolution, pulse time characteristics, radioactive background, compliance detection efficiency, memory effect, and minimum detectable activity to determine whether the gas detector is available and can perform long-term stable measurements Very low activity radioactive xenon.

The cleaning of the traditional gas detector requires repeated pumping and inflation due to the memory effect of the gas detector, which is time-consuming and labor-intensive. Moreover, due to the structural characteristics of the gas detector, the pressure range must be precisely controlled, which is not allowed. The use of overpressure makes it difficult to clean the gas detector.

SUMMARY OF THE INVENTION

In view of this, the present invention aims to provide a gas filling method for a gas detector, which is simple in operation, saves time and labor, and can efficiently clean the gas detector and fill the radioactive xenon gas sample.

The specific sampling of the present invention is as follows:

A method for filling a gas detector with gas, the method for filling a gas detector with gas comprises:

Step S: first, repeatedly cleaning the gas detector;

Step T: then fill the gas detector with a calibrated atmospheric pressure radioactive xenon gas sample;

Wherein, step S specifically includes the following steps:

S1. Connect the gas detector to the pipeline valve V6, open the pipeline valves V3, V4 and the valve of the gas detector; start the vacuum pump, when the pressure displayed by the absolute pressure sensor is greater than the preset pressure threshold, switch the pipeline valve V5 alternately and V6 to pump the gas detector. At this time, the opening and closing status of the pipeline valves V5 and V6 is one of the following three combinations, one is that the pipeline valve V5 is opened, the pipeline valve V6 is closed, and the other is the pipeline valve V5 is closed. , the pipeline valve V6 is open, the third is that the pipeline valve V5 is closed, and the pipeline valve V6 is closed; when the pressure displayed by the absolute pressure sensor is not greater than the preset pressure threshold, close the pipeline valve V4, keep the pipeline valves V3, V5 and V6 open, and the gas The detector is exhausted;

S2. Open the valve V1-3 of the cylinder III, fill the cylinder III with high-purity helium gas whose pressure value is lower than the maximum working pressure of the gas detector, close the valve V1-3 of the cylinder III, and the filling of the cylinder III is completed. ;

S3. Open the self-contained valve V2-3 of the cylinder III, fill the helium gas in the cylinder III into the gas detector until the pressure value of the absolute pressure sensor remains unchanged, and close the self-contained valve V2-3 of the cylinder III and the pipeline valve V6, the gas detector is inflated;

S4. Open the pipeline valve V4, and alternately switch the pipeline valves V5 and V6 to pump the gas detector. When the pressure displayed by the absolute pressure sensor is not greater than the preset pressure threshold, close the pipeline valve V4 and keep the pipeline valves V3 and V5. And V6 is turned on, the gas detector pumping ends;

S5. Repeat steps S3 to S4 until the residual radioactive xenon gas sample volume in the gas detector is lower than the preset reference value, stop repeating steps S3 and S4, close the vacuum pump, and restore all valves to the closed state;

Among them, the cylinder III, the absolute pressure sensor and the components of the vacuum pump are connected through stainless steel pipes and pipeline valves V3~V6, and the initial state of the valves are all closed; the cylinder III, the absolute pressure sensor and the gas detector are respectively located at One end of the cross interface; the front end of the air inlet of the cylinder III is connected to the external air source; the valve V1-3 of the cylinder III is located on one side of the cylinder III, and the valve V2-3 of the cylinder III is located on the other side of the cylinder III.

Further, wherein, in step T, filling the gas detector with a calibrated atmospheric pressure radioactive xenon gas sample specifically includes the following steps:

T1. Open the pipeline valves V3, V4 and the built-in valve of the gas detector, start the vacuum pump, and alternately switch the pipeline valves V5 and V6. When the gas detector is in a low vacuum state, close the pipeline valves V4 and V5, close the vacuum pump, and keep the pipeline The valve V3, the pipeline valve V6 and the built-in valve of the gas detector are opened;

T2. Open the self-contained valve V1-4 of the cylinder IV, fill the calibrated atmospheric pressure radioactive xenon gas sample from the outside into the gas detector, and close the self-contained valve V1-4 of the cylinder IV;

T3. Open the self-contained valve V2-4 of the cylinder IV. When the pressure value of the absolute pressure sensor is stable, close the self-contained valve V2-4, the pipeline valve V3, the pipeline valve V6 and the gas detector of the cylinder IV. With valve, the gas detector is filled with atmospheric pressure radioactive xenon gas sample;

Among them, the valve V1-4 of the cylinder IV is located on one side of the cylinder IV, and the valve V2-4 of the cylinder IV is located on the other side of the cylinder IV.

Further, when the gas detector is cleaned in the step S, the volume of the cylinder III is about 125 times the volume of the gas detector, and the pressure in the cylinder III is 10-20 kPa lower than the maximum operating pressure of the gas detector.

Further, when the gas detector is filled with the calibrated atmospheric pressure radioactive xenon gas sample in the step T, the volume of the cylinder IV is the same as the filled volume of the calibrated atmospheric pressure radioactive xenon gas sample.

Further, the preset pressure threshold in step S1 is 20 kPa.

Further, the preset reference value in step S5 is 1% of the initial volume of the radioactive xenon gas sample in the gas detector before the gas detector is cleaned in step S.

As an auxiliary technology specially used for the determination of some basic performance parameters of the gas detector, the invention adopts the pipeline vacuuming buffer technology, which can efficiently carry out the cleaning to prevent the memory effect, and fill the radioactive xenon gas sample required for calibrating the relative detection efficiency; Simple, time-saving and labor-saving, it satisfactorily solves the requirements of narrow pressure range, high pressure precision control and repeated operation of gas detectors, and provides solid technical support for the development of gas detectors.

Description of drawings

Fig. 1 is a schematic diagram of an auxiliary device dedicated to the method for filling gas into a gas detector of the present invention;

Fig. 2 is the flow chart of the method for filling gas in the gas detector of the present invention;

In the figure, 1. Cylinder group 11. Cylinder I 12. Cylinder II 13. Cylinder III 14. Cylinder IV 2. Absolute pressure sensor 3. Buffer column 4. Vacuum pump;

Among them, V1-1, V1-2, V1-3, V1-4 represent the self-contained valves on the side of cylinder I11, cylinder II12, cylinder III13, and cylinder IV14, respectively, V2-1, V2-2, V2-3, V2 -4 represents the valves on the other side of cylinder I11, cylinder II12, cylinder III13, and cylinder IV14, respectively, and V3~V6 are pipeline valves.

Detailed ways

The present invention will be further explained in detail below with reference to FIG. 1 and FIG. 2 .

As shown in FIG. 2 , the method for filling the gas detector with gas according to the present invention includes the following steps: Step S: first, repeatedly cleaning the gas detector to eliminate the influence of memory effect on the measurement accuracy; Step T: then charging the gas detector The atmospheric pressure radioactive xenon gas sample that has been calibrated (that is, the specific activity is known) is entered for the calibration of the relative detection efficiency method of the gas detector.

Wherein, step S specifically includes the following steps:

S1. Connect the gas detector to the pipeline valve V6, open the pipeline valves V3, V4 and the valve of the gas detector; start the vacuum pump, when the absolute pressure sensor 2 shows a pressure greater than the preset pressure threshold, switch the pipeline valve alternately V5 and V6 are used to pump the gas detector. At this time, the opening and closing status of the pipeline valves V5 and V6 is one of the following three combinations, one is the pipeline valve V5 is open, the pipeline valve V6 is closed, and the other is the pipeline valve V5 Close, pipeline valve V6 is open, thirdly, pipeline valve V5 is closed, pipeline valve V6 is closed; when the pressure displayed by the absolute pressure sensor is not greater than the preset pressure threshold, close pipeline valve V4, keep pipeline valves V3, V5 and V6 open, The gas detector is exhausted;

S2. Open the valve V1-3 of the cylinder III13, fill the cylinder III13 with high-purity helium gas whose pressure value is lower than the maximum working pressure of the gas detector, close the valve V1-3 of the cylinder III13, and the filling of the cylinder III13 is completed. ;

S3. Open the valve V2-3 of the cylinder III13, and fill the helium gas in the cylinder III13 into the gas detector. After a few seconds, until the pressure value of the absolute pressure sensor 2 remains unchanged, close the valve of the cylinder III13. V2-3 and pipeline valve V6, the gas detector is inflated;

S4. Open the pipeline valve V4, and alternately switch the pipeline valves V5 and V6 to pump the gas detector. When the pressure displayed by the absolute pressure sensor 2 is not greater than the preset pressure threshold, close the pipeline valve V4 and keep the pipeline valve V3, V5 and V6 are turned on, and the gas detector is exhausted;

S5. Repeat steps S3 to S4 until the residual radioactive xenon gas sample volume in the gas detector is lower than the preset reference value, stop repeating steps S3 and S4, close the vacuum pump, and restore all valves to the closed state.

Further, in step T, filling the gas detector with a calibrated atmospheric pressure radioactive xenon gas sample specifically includes the following steps:

T1. Open the pipeline valves V3, V4 and the valve of the gas detector, start the vacuum pump 4, switch the pipeline valves V5 and V6 alternately, when the gas detector is in a low vacuum state, close the pipeline valves V4 and V5, close the vacuum pump, keep The pipeline valve V3, V6 and the built-in valve of the gas detector are opened;

T2. Open the self-contained valve V1-4 of the cylinder IV14, fill the calibrated atmospheric pressure radioactive xenon gas sample from the outside into the gas detector, and close the self-contained valve V1-4 of the cylinder IV14;

T3. Open the valve V2-4 of the cylinder IV14. After a few seconds, when the pressure value of the absolute pressure sensor 2 is stable, close the valve V2-4, the pipeline valve V3 and the pipeline valve V6 of the cylinder IV14. and the gas detector's own valve, and end filling the gas detector with the atmospheric pressure radioactive xenon gas sample. Disassemble the gas detector and use it for the calibration of its relative detection efficiency method.

Further, when the gas detector is cleaned in step S, the volume of the cylinder III13 is about 125 times the volume of the gas detector, and the pressure in the cylinder III13 is 10-20 kPa lower than the maximum operating pressure of the gas detector. In this way, it not only meets the requirements of miniaturization of the device, but also continuously cleans the gas detector for more than 30 times at a pressure slightly higher than normal pressure, so as to eliminate the influence of the memory effect on the measurement accuracy of the gas detector in a short period of time, and also Reduce the device's dependence on external air sources.

Further, when the gas detector is filled with the calibrated atmospheric pressure radioactive xenon gas sample in step T, the volume of the cylinder IV14 is the same as the volume of the calibrated atmospheric pressure radioactive xenon gas sample, so as to ensure that the calibrated atmospheric pressure radioactive xenon gas sample has been filled. The atmospheric pressure radioactive xenon gas sample is completely desorbed and at atmospheric pressure, which meets the requirements of the gas detector measurement and accurately obtains the detection efficiency of the gas detector.

Further, the preset pressure threshold in step S1 is set according to the pressure use range of the gas detector, for example, the preset pressure threshold is set as 20kPa.

Further, the preset reference value in step S5 is 1% of the initial volume of the radioactive xenon gas sample in the gas detector before the gas detector is cleaned in step S.

The present invention also provides a specific device specially used for the gas filling method of the gas detector of the present invention, that is, an auxiliary device specially used for the gas filling method of the gas detector of the present invention, as shown in FIG. 1 . The device of the present invention will be described in further detail below in conjunction with FIG. 1 .

As shown in FIG. 1, the auxiliary device of the present invention specially used for the gas filling method of the gas detector includes: a steel cylinder group 1, an absolute pressure sensor 2, a buffer column 3 and a vacuum pump 4, and the stainless steel pipes and valves are used between the components to carry out The initial state of the valve is closed, wherein the cylinder group 1, the absolute pressure sensor 2, the buffer column 3 and the gas detector are respectively located at one end of the cross interface; the cylinder group 1 includes four parallelly arranged steel cylinders I11 and cylinder II12, cylinder III13 and cylinder IV14; the front end of the gas inlet of cylinder group 1 is connected to an external gas source, and the external gas source is a high-purity helium source or a calibrated atmospheric pressure radioactive xenon gas sample; the rear end of buffer column 3 Connected to vacuum pump 4.

Further, the cylinder group 1 is a flow-wash stainless steel cylinder with two valves V1 and V2. Specifically, cylinder I11 has its own valve V1-1 and valve V2-1, cylinder II12 has its own valve V1-2 and valve V2-2, cylinder III13 has its own valve V1-3 and valve V2-3, and cylinder IV14 has its own valve V1-4 and valve V2-4. The present invention selects suitable steel cylinders according to different working purposes, and the pressure of the inflatable body in the steel cylinder needs to be controlled within a reasonable range in order to match the pressure range of the gas detector. Since the sample chamber of the gas detector is made of plastic scintillators, it is neither resistant to low vacuum nor high pressure. It is necessary to strictly control the inflation pressure of the gas detector. For this reason, different steel cylinders are used to match it, which is safe and efficient. to complete the predetermined function. During leak detection, the pressure of the control gas detector is at the upper limit of the operating pressure range (for example, 140kPa); when cleaning, the pressure range of the control gas detector is within a reasonable range (for example, 20kPa~120kPa); When the radioactive xenon gas sample is used, the instantaneous low pressure of the control gas detector is not less than 0.1kPa, and the final pressure of inflation is controlled at about normal pressure (95kPa).

When the device of the present invention is used for gas detector relative detection efficiency calibration of radioactive xenon gas sample, firstly, the gas detector is repeatedly cleaned to eliminate the influence of memory effect on measurement accuracy; Atmospheric radioactive xenon gas sample.

Further, when cleaning the gas detector, choose a cylinder III13 with a volume of about 125 times the volume of the gas detector, and fill it with high-purity helium that is slightly lower than the maximum working pressure of the gas detector, which not only meets the requirements of miniaturization of the device, but also can The gas detector is continuously cleaned for more than 30 times at a pressure slightly higher than normal pressure, so as to eliminate the influence of the memory effect on the measurement accuracy of the gas detector in a short time, and also reduce the dependence of the device on the external gas source; when the cylinder When the pressure in III13 is lower than 100kPa, supplement the high-purity helium gas in cylinder III13 to slightly lower than the maximum operating pressure of the gas detector.

Further, when the gas detector is calibrated by the relative efficiency method, the cylinder IV14 is filled with the calibrated atmospheric pressure radioactive xenon gas sample, and the appropriate volume of the cylinder IV14 is selected to ensure that the atmospheric pressure radioactive xenon gas sample that has been calibrated is completely desorbed. And it is at normal pressure, which meets the requirements of the gas detector measurement, and accurately obtains the detection efficiency of the gas detector.

Further, the absolute pressure sensor 2 has a measurement range of 0 to 200 kPa and an accuracy of 0.25%, which ensures the accuracy of the pressure displayed by the device.

Further, the buffer column 3 is a metal tube, its volume is equivalent to that of the gas detector, and the shape is preferably a spiral type, which ensures the miniaturization of the device, and can control the pressure of the gas detector to be in a suitable range, and clean as much as possible. At the same time, it is also necessary to reduce the number of operations and shorten the time required for the operation.

Further, the pumping speed of the vacuum pump 4 is several liters per second, which ensures that the auxiliary device can be quickly evacuated to a desired vacuum degree, and saves the time required to complete the work of the predetermined function.

As an auxiliary technology specially used for the determination of some basic performance parameters of the gas detector, the invention adopts the pipeline vacuum buffer technology, which can effectively clean the gas detector and charge the radioactive xenon gas sample required for calibrating the relative detection efficiency; It meets the requirements of narrow pressure range, high pressure precision control and many repeated operations for gas detectors, and provides solid technical support for the development of gas detectors.

The particular embodiment of the invention described is but one easier of the various possibilities. All relevant implementation cases are exemplary rather than exhaustive, and the invention is by no means limited to the described implementation cases. Many modifications and variations are possible and apparent without departing from the scope and spirit of the embodiments of the present invention.

Claims (6)

1. A method for filling a gas detector with gas, wherein the method for filling a gas detector with gas comprises: Step S: first, repeatedly cleaning the gas detector; Step T: then fill the gas detector with a calibrated atmospheric pressure radioactive xenon gas sample; Wherein, step S specifically includes the following steps: S1, connect the gas detector to the pipeline valve V6, open the pipeline valves V3, V4 and the valves of the gas detector; start the vacuum pump, when the absolute pressure sensor (2) shows the pressure When the pressure is greater than the preset pressure threshold, alternately switch the pipeline valves V5 and V6 to pump the gas detector. At this time, the opening and closing status of the pipeline valves V5 and V6 is one of the following three combinations. One is that the pipeline valve V5 is opened. , the pipeline valve V6 is closed, the second is the pipeline valve V5 is closed, the pipeline valve V6 is open, the third is the pipeline valve V5 is closed, the pipeline valve V6 is closed; when the absolute pressure sensor shows the pressure is not greater than the preset pressure threshold, close the pipeline valve V4 , keep the pipeline valves V3, V5 and V6 open, and the gas detector is exhausted; S2. Open the valve V1-3 of the cylinder III (13), fill the cylinder III (13) with external high-purity helium with a pressure value lower than the maximum working pressure of the gas detector, and close the self-contained valve of the cylinder III (13). Valve V1-3, cylinder III (13) is inflated; S3. Open the valve V2-3 of the cylinder III (13), fill the helium gas in the cylinder III (13) into the gas detector, until the pressure value of the absolute pressure sensor (2) remains unchanged, close the cylinder III ( 13) The self-contained valve V2-3 and the pipeline valve V6, the gas detector is inflated; S4. Open the pipeline valve V4, and alternately switch the pipeline valves V5 and V6 to pump the gas detector. When the pressure displayed by the absolute pressure sensor (2) is not greater than the preset pressure threshold, close the pipeline valve V4 and keep the pipeline valve V3, V5 and V6 are turned on, and the gas detector is exhausted; S5. Repeat steps S3 to S4 until the residual radioactive xenon gas sample volume in the gas detector is lower than the preset reference value, stop repeating steps S3 and S4, close the vacuum pump, and restore all valves to the closed state; Among them, the steel cylinder III (13), the absolute pressure sensor (2) and the components of the vacuum pump are connected through stainless steel pipes and pipeline valves V3~V6, and the valves are in the closed state at the initial state; the steel cylinder III (13), the absolute pressure The pressure sensor (2) and the gas detector are respectively located at one end of the cross interface; the front end of the air inlet of the cylinder III (13) is connected to the external air source; the valve V1-3 of the cylinder III (13) is located at the cylinder III (13) On one side of the cylinder III (13), the valve V2-3 of the cylinder III (13) is located on the other side of the cylinder III (13). 2. The method for filling a gas detector with gas as claimed in claim 1, wherein, in step T, filling the gas detector with a calibrated atmospheric pressure radioactive xenon gas sample specifically comprises the following steps: T1. Open the pipeline valves V3, V4 and the valve of the gas detector, start the vacuum pump (4), switch on and off the pipeline valves V5 and V6 alternately, when the gas detector is in a low vacuum state, close the pipeline valves V4 and V5, and turn off the vacuum pump , keep the pipeline valve V3, pipeline valve V6 and the built-in valve of the gas detector open; T2. Open the self-contained valve V1-4 of the cylinder IV (14), fill the calibrated atmospheric pressure radioactive xenon gas sample from the outside into the gas detector, and close the self-contained valve V1-4 of the cylinder IV (14); T3. Open the valve V2-4 of the cylinder IV (14), when the pressure value of the absolute pressure sensor (2) is stable, close the valve V2-4 of the cylinder IV (14), the pipeline valve V3, Pipeline valve V6 and the gas detector's own valve, finish filling the gas detector with atmospheric pressure radioactive xenon gas sample; Among them, the valve V1-4 of the cylinder IV (14) is located on one side of the cylinder IV (14), and the valve V2-4 of the cylinder IV (14) is located on the other side of the cylinder IV (14). 3 . The method for filling a gas detector with gas according to claim 1 , wherein when the gas detector is cleaned in step S, the volume of the steel cylinder III ( 13 ) is about the volume of the gas detector. 4 . 125 times, the pressure in the cylinder III (13) is 10~20kPa lower than the maximum operating pressure of the gas detector. 4. The method for filling a gas detector with gas according to claim 2, wherein when the gas detector is filled with a calibrated atmospheric pressure radioactive xenon gas sample in the step T, the cylinder IV (14 ) is the same volume as the filled calibrated atmospheric pressure radioactive xenon gas sample. 5 . The method for filling a gas detector with gas according to claim 1 , wherein the preset pressure threshold in step S1 is 20 kPa. 6 . 6. The method for filling a gas detector with gas according to claim 1, wherein the preset reference value in step S5 is the value of the radioactive xenon gas sample in the gas detector before cleaning the gas detector in step S. 1% of the initial volume.

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